If you are installing specfem3d for the first time on CentOS 7, you may want to note the following suite of software we use

• GNU-6.5.0
• OpenMPI-3.1.4
• specfem3d
• CentOS-7

$ git clone --recursive --branch devel https://github.com/geodynamics/specfem3d.git

$ ./configure CC=gcc MPIFC=mpif90 MPI_INC=/usr/local/openmpi-3.1.4/include

$ make